Lemon peel oil (LPO) is a promising alternative biofuel for diesel engine applications due to its favorable physical and chemical properties. This study deals with combustion, vibration, and noise measurement for diesel engine powered with biofuel blend in the perspective of passenger comfort at engine idle condition. Experimentation is performed using a 20% blend of lemon peel oil with diesel (B20) according to central composite design (CCD) by varying pilot mass (PM), pilot injection timing (PIT), injection pressure, and engine speed (ES). Vibrations at engine crankcase, cylinder head were measured with a triaxial accelerometer along with noise measurement. The output responses for diesel and B20 were compared based on the output from response surface methodology (RSM). The study observed that predominant vibrations at the crankcase level along the lateral direction of the engine influenced by fuel injection pressure (FIP) and engine speed for both test fuels. Engine head vibrations were maximum along with the reciprocating motion of piston for both test fuels and found 7.43% more in case diesel. Engine noise is comparable from both test conditions irrespective of different influencing parameters. An increment of 1.662 J/deg in the heat release rate (HRR) of B20 is observed attributed to a longer ignition delay of B20 fuel. This study concludes that the lemon peel oil blend is compatible to use as an alternate biofuel in a diesel engine with suitable damping techniques for better passenger comfort. © 2021 American Society of Mechanical Engineers (ASME). All rights reserved.